Geraniums are popular annual plants that flower in late spring through the first frost of the fall. The plants are easy to start from seed; however, they grow slowly, taking 12 to 16 weeks to produce flowers after seeding. Start geranium seeds in late January so the plants are ready to produce blooms in spring. Grow geraniums in full sun conditions and keep the soil moist for best results.
Lay geranium seeds on half of the surface of several damp paper towels. Fold the towels over and cover the seeds. Place the towels and seeds in a plastic bag and secure closed. The seeds will begin to germinate in 24 hours.
Moisten sterile seed-starting soil by placing it in a large container with enough water to make the soil feel spongy but not wet. Let the soil absorb the water for 1 to 2 hours.
Fill seed-starting trays with moistened soil. Pack the soil lightly and add two to three seeds to each pot or seed-starting divot. Cover the seeds with 1/4 inch of seed-starting soil. Water the seeds lightly using a water misting bottle.
Cover the pots with a clear plastic cover or a plastic bag to simulate a greenhouse. Place the seeds in a location with a temperature of 70 to 75 degrees F. Sunlight is not needed for germination.
Open the plastic covering enough to allow for air circulation once green spouts are present. Move the seedlings under grow lights or in an area where sunlight is present for 12 to 14 hours per day. Remove the cover completely once the first two true leaves appear.
Transplant the seedlings to individual pots 1 to 2 weeks after the emergence of two true leaves. Keep the soil moist, but not wet. Fertilize the seedlings with a half-strength diluted water-soluble fertilizer.
Pinch off the seedling tops once they begin to grow strongly. This will keep the plant compact.